1. Overview
Display technology (e.g., for use in computer and entertainment display devices) continues to advance, as generally is the case with consumer and business electronics. One particular type of display device that is commonly used is projection display systems (hereafter “projectors”), such as digital display systems. A wide variety of such a projection systems is available from InFocus Corporation of Wilsonville, Oreg., the assignee of the present application.
Projectors, such as those manufactured by InFocus, typically include an optical subsystem that integrates light from an illumination source (e.g., a high pressure mercury lamp) for projecting images (e.g., still or moving) onto a display surface, such as a screen or wall. One component that may be included in the optical subsystem of such projectors is a light tunnel, which operates as a light integrating device. The operation of one embodiment of a light tunnel is described in U.S. Pat. No. 6,419,365 to Potekev et al., which is assigned to InFocus, the assignee of the present application. U.S. Pat. No. 6,419,365 is incorporated by reference herein in its entirety.
It may be necessary, from time to time, to “adjust” such light tunnels (or the path of light communicated out of the tunnel) so that the tunnel (or light from the tunnel) is properly aligned with other components of the optical subsystem (e.g., a light source, lenses). For example, light tunnel adjustments are typically done during the manufacture of the projector. In addition to the initial light tunnel adjustment performed during manufacturing, subsequent adjustments may be needed if, for example, the projected is physically jarred resulting in the light tunnel becoming misaligned due to such a mechanical shock. Further, such an adjustment may be made during service of the projector, such as when one or more components of the optical subsystem are replaced.
2. Current Adjustment Techniques
Two common approaches that are used for adjusting the path of integrated light produced by a light tunnel are mechanical adjustment of the light tunnel and mechanical adjustment of another component of the optical subsystem, such as a mirror device. In applications employing mechanical adjustment of the light tunnel, the adjustment is accomplished by physically moving the light tunnel with respect to the other components in the system. For example, one end of the light tunnel may be moved while the other end of the light tunnel remains in a fixed position with respect to an illumination source. Such light tunnel adjustment is typically done orthogonally, along multiple Cartesian axes (e.g., the x-axis and the y-axis, with the z-axis being fixed), though other mechanical adjustment techniques may be used. Current approaches for effecting such adjustments, however, employ numerous parts and are somewhat mechanically complex. In comparison, for applications employing mechanical adjustment of another optical component in the projector, the light tunnel is mounted in a fixed position and an optical path of the integrated light produced by the tunnel is adjusted by mechanically adjusting the alignment of the other optical component, such as a mirror device, a lamp, or any other suitable component. Such adjustments are effected using techniques that have similar mechanical complexity as techniques for mechanical adjustment of a light tunnel.
An example of a prior art system that employs mechanical adjustment of a light tunnel is shown in FIGS. 1 and 2. FIG. 1 shows a disassembled light tunnel mounting and adjustment assembly (hereafter “tunnel assembly”) 100. The tunnel assembly 100 includes a light tunnel 110 that is used to integrate light from a light source (not shown) for use in the projection of images. The tunnel is mounted inside of a two part clamshell mounting tube 120, which is in turn mounted inside a main optics chassis 130. Retention springs 140 are located around the sides of the tunnel 110 when mounted in the mounting tube 120 (e.g., between the inner surface of the mounting tube 120 and the exterior surface of the light tunnel 110). The springs 140 each exert a force on the sides of the light tunnel 110 to fixedly retain it in position in the mounting tube 120. Adjustment screws 150 are threaded through the optics housing 130 and also may extend through the sides of the mounting tube 120. The adjustment screws 150 are used to adjust the alignment of the light tunnel 110 in the tunnel assembly 100. To effect such an adjustment, the screws exert a force on the light tunnel 120 (either directly or indirectly) to move it along a respective Cartesian axis (e.g., the x-axis or the y-axis). The compliance of the springs 140 allows for such movement of the light tunnel 110.
FIG. 2 illustrates the location of the adjustment screws 150 in the optics housing 130. Once an adjustment to the alignment of the light tunnel 110 in the tunnel assembly 100 is made, the forces exerted on the light tunnel 100 by the springs 140 and the adjustment screws 150 retain the light tunnel 110 fixedly in the new alignment position.
The tunnel assembly 100 further includes a shield 160. The shield 160 protects the light tunnel from excessive light, heat and/or radiation generated by the light source of a projector in which the tunnel assembly is implemented. Such excessive light, heat and/or radiation would otherwise cause thermal damage to adhesives and optical coatings that are included in the light tunnel 110.
FIGS. 3 and 4 illustrate an alternative, prior art light tunnel assembly 300, which employs mechanical tunnel adjustment techniques. In FIGS. 3 and 4, elements that are analogous with the elements of FIGS. 1 and 2 are referenced with like 300 series numbers. FIG. 3 shows, in similar fashion as FIG. 1, a disassembled tunnel assembly 300. The tunnel assembly 300 includes a light tunnel 310 and a clamshell mounting tube 320. The light tunnel 310, however, includes a shield 360 to protect the light tunnel 310 from excessive light, heat and radiation, as opposed to the discrete shield 160 the tunnel assembly 100. The shield 360 in FIG. 3 is an adhesive backed metal foil that is affixed to the light tunnel 310.
The tunnel assembly 300 also includes a main optics chassis 330 in which the assembled light tunnel 310 and mounting tube 320 are installed. Retention springs 340 are installed on the inner surface of the mounting tube 320 on posts 342. As with the springs 140 in the tunnel assembly 100, the springs 340 each exerts a force on a respective side of the tunnel 310 to fixedly retain it in position in the mounting tube 320. Adjustment screws 350 are inserted through the optics housing 330 and may extend through the posts 342. The adjustment screws 350 are used to adjust the alignment of the light tunnel 310 in the tunnel assembly 300. To effect such an adjustment, the screws exert a force on the light tunnel 320 (either directly or indirectly) to move it along a respective axis (e.g., the x-axis or the y-axis). The compliance of the springs 340 allows for such movement of the light tunnel 310. Once an adjustment to the alignment of the light tunnel 310 in the tunnel assembly 300 is made, the forces exerted on the light tunnel 310 by the springs 340 and the adjustment screws 350 retain the light tunnel 310 fixedly in the new alignment position.
As may be seen from FIGS. 1–4, the tunnel assemblies 100, 200 includes numerous parts and are somewhat complex in construction. Such assemblies may require a high level of precision in manufacturing to insure that all of the components of the tunnel assembly are properly installed and that the tunnel assemblies will mechanically operate (e.g., adjust) as expected. Therefore, light tunnel assemblies that are less complex and employ fewer parts are desirable.
Referring to FIG. 5, a light tunnel retention mechanism 500 is shown. The retention mechanism 500 is implemented in a light tunnel assembly that employs mechanical alignment of a mirror device. The retention mechanism 500 is employed to retain a light tunnel 510 in a fixed position in an optics chassis 530. The light tunnel 510 is held fixedly in place by two y-axis spring fingers 540 and two x-axis spring fingers 545. Additionally, the light tunnel 510 is held in place in the z-axis by the optics chassis 530 and the retention mechanism 500.
As may be seen in FIG. 5, the retention mechanism 500 is installed over posts 536, which may properly align the retention mechanism with the optics chassis for retaining the light tunnel 510 in a fixed position. For the tunnel assembly shown in FIG. 5, mechanical adjustment of the tunnel position is not possible. Once the retention mechanism 500 is installed, in the tunnel assembly of FIG. 5, the light tunnel 510 will remain in a substantially fixed position.
For the tunnel assembly shown in FIG. 5, light tunnel adjustment is accomplished by mechanically adjusting another component in the optical subsystem. Specifically, an optical device, such as a mirror device (not shown) is mechanically adjusted to modify the path of integrated light from the light tunnel 510. Thus, while the projector of FIG. 5 employs fewer components for retaining the light tunnel 510 than the tunnel assemblies shown in FIGS. 1–4, the projector of FIG. 5 additionally requires a mechanical system to adjust the alignment of a mirror device (or other component) that is of similar mechanical complexity to the light tunnel adjustment systems shown in FIGS. 1–4.